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تعداد نتایج: 111 فیلتر نتایج به سال:
A disposable sensor has been developed for the measurement of copper(II) concentration in aqueous solution based on a change in the fluorescence of porphyrazine 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (TP). The sensor was constructed by spin-coating a polyester support with a PVC solution containing TP, a plasticizer, the chelating agent Zincon and the ion-pairing benzet...
A PVC-based membrane electrode for thallium(I) ions based on 1,21,23,25-tetramethyl-2,20: 3,19-dimetheno[H, 2] H, 23H, 25H-bis-[1,3] dioxocino[5,4-i:5',4'-i] benzo [1,2-d: 5.4-d'] bis [1,3] benzodioxocin(II) has been prepared. The electrode displays a linear dynamic range of 1.0 × 10−1-1.0 × 10−5 M, with a Nernstian slope of 59.8 ± 0.2 mV decad−1, and a detection limit 5.0 × 10−6 M. It has a ve...
Porphyrin self-assembly at electrochemical interfaces: role of potential modulated surface mobility.
The self-assembly of 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) on Au(111) electrodes was investigated. The adlayer structure was found to depend on the electrode potential. At positive potentials (>0.5V(SCE)), a disordered layer of TPyP is formed on the Au(111) electrode. STM images showed that the disordered molecules are immobile. At negative potentials (-0.2V(SCE)), however, the mo...
Porphyrins and metalloporphyrins are promising new protein labels that can be detected using multiple techniques; improving the reliability of the analysis and broadening the range of the linear response. Here, we investigate the potential of 5,10,15,20-tetraphenyl-21H,23H-porphyrin (Tpp) as a hybrid protein label. The electrochemical and optical properties of porphyrin conjugated with bovine s...
A novel series of mesotetrakis[aryl]-21H,23H-porphyrin derivatives 2a-j was synthesized from the condensation of aldehyde derivatives 1a-j with pyrrole in the presence of p-toluenesulfonic acid. The synthesized porphyrins were considered as a model to study the free radical-induced damage of biological membranes and the protective effects of these porphyrins. It was found that these compounds e...
The interactions of the ILPR sequence (ILPR = "insulin-linked polymorphic region") a2 [d(ACAG4TGTG4ACAG4TGTG4)] with [2.2.2]heptamethinecyanine derivatives 1a-e and with the already established quadruplex ligands coralyne (2), 3,3'-[2,6-pyridinediylbis(carbonylimino)]bis[1-methylquinolinium] (3), 4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis[1-methylpyridinium] (4), naphtho[2,1-b:...
Modificações no sinal de absorção de estado excitado da 5,10,15,20-tetra(4-piridil)-21H,23Hporfirina, provocadas tanto pela substituição do íon central quanto pela adição de grupos periféricos, são investigadas empregando-se pulsos laser de 5 ns com 532 nm, juntamente com medidas de absorção linear e tempo de decaimento da fluorescência. A absorção saturada reversa (RSA) aumenta consideravelmen...
Magnetic circular dichroism (MCD) spectroscopy provides extended information about molecular electronic structure and transitions. Because the chirality is induced by static magnetic field it can also be used for non-chiral compounds. However, interpretation of the spectra is difficult, and precise computations using quantum mechanical approaches were implemented in publicly available software ...
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